Polycyclic Aromatic Hydrocarbons and Male Reproductive Health Despite heightened concerns over reported declines in sperm quality;a lack of epidemiologic data exists regarding a link to job-related environmental exposure. Increasing evidence, however, from animal studies has shown that polycyclic aromatic hydrocarbons (PAHs) contribute to male rat reproductive system dysfunction. At the same time, PAH exposure as a contributing factor to male reproductive health in humans is still inconclusive. The long term goals of the project are: i) to develop field data collection methods to monitor human occupational exposure to PAHs;ii) to evaluate the reproductive altering potential of the exposure;iii) to evaluate the influence of genetic susceptibility to PAH exposure;and ultimately iv) to distribute the information to protect workers'health and safety. We hypothesize that PAH exposure contributes to decreased sperm quality of coke-oven workers, especially those with susceptible gene polymorphisms. The research component describes a cross-sectional study to characterize coke-oven workers'sperm quality, quantify PAH biomarker levels, and detect allelic variants in CYP1A1 and GSTM1 genes. Urine samples will be collected for determining PAH internal exposure levels. Baseline serum samples will be collected for genotype analysis of CYP1A1 and GSTM1 allelic variants. Semen will be collected to assess sperm quality and DNA integrity, and PAH-DNA adducts. Features of this design include efficient control for confounding factors, accurate exposure ascertainment, sufficient power to detect exposure related changes in reproductive indicators;and design efficiency to evaluate polymorphic influence on PAH metabolization. Research results may prompt reforms in workplace practices and policies to protect the reproductive health of workers exposed to PAHs. Public Health Relevance: The study aims to assess individual coke-oven workers'susceptibility to PAHs from occupational exposure, which may cause decreased sperm quality.